The invention is concerned with a polystyrene-based foam and a method to produce such foam for the production f.e. of label material.
Such foams are known in various embodiments. Reference is made for example to DE-A1 40 11 003. This state of the art refers to a foam, which has recently been developed in order to avoid CFCs by using blowing agents in form of hydrocarbons, carbondioxides, nitrogenes, combinations thereof etc. Before, is has also been known to produce foams using chemical blowing agents together with nucleating agents, see for example EP-A3-055 437.
A technical problem with such polystyrene-based foams is especially their brittleness, resulting in easy tearing and inferior elasticity. In order to improve these properties, it has already been proposed to put the polystyrene-based foam as one layer in a multi-layer foam, with one of the layers being a polyolefinic layer. However, this is affected with comparatively high production costs and extrusion problems. As it is often desired, for recycling purposes, to have only one kind of material, such multi-layer foam consisting of different plastic materials, may create also problems.